Question: What are the group or class of chemical substances which start with the letter v
Paraphrase: What are the bunch or lesson of chemical substances which begin with the letter v
SPARQL (Wikidata): SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q17339814 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'v')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
Answer: vitamin E, vitamin E, volcanic ash, volcanic ash, vitamin B6, vitamin B6, vitamin B, vitamin B, vitamin K, vitamin K, vitamin A, vitamin A, virulence factor, virulence factor, venturicidins, venturicidins, Vasopressin  receptor agonist, Vasopressin  receptor agonist, vinyl toluene, vinyl toluene, vermixocin, vermixocin, vitamin B1 analogue, vitamin B1 analogue